Oxidizing reactions of azines. 8. One-reactor oxidation of 4-aryl and 4-methyl-1,2,3,6-tetrahydropyridines to 1-formylamino-substituted alkan-3-ones

One-reactor oxidation by potassium permanganate has been carried out for a series of 4-aryl- and 4-methyl-l,2,3,6-tetrahydropyridines to give 1-formylamino-substituted 3-arylpropan-3-ones and butan-3-ones. The effect has been studied of the nature of the substrate, the temperature, and interphase transfer catalysts on the yield of amino alkanone. It is proposed that the reaction proceeds through the intermediate formation of 3,4-dihydroxypiperidin-2-ones which then undergo oxidative decyclization with elimination of one carbon atom.